rework frame_id support

[bmegli]

Existing support is not correct.

This pull request:

• takes some steps back removing existing frame_id code
• starts with simple frame_id support
  • also for multisource and multipart

More work can be added on top

---

• remove frame_id from dynamic reconfigure
  • it is terrible idea to reconfigure frame_id at runtime
  • dynamic reconfigure was overwriting launchfile frame_id with camera on init
• isolate code related to frame_ids
  • were constructed in multiple places
  • without consistency
• remove tf optical publishing code
  • weren't used (images published under different frames!)
  • doesn't probably even need to be coded
  • didn't support multisource and multipart
• add support for defining multisource and multipart frame_ids
  • support multipart , and multisource ; separators in args